Load transformer and differential amplifier

Abstract

The present invention relates to the technical field of wireless communications. Provided are a load transformer and a differential amplifier. The load transformer comprises a first metal layer, a second metal layer, a third metal layer and a fourth metal layer which are sequentially stacked, wherein the first metal layer, the second metal layer, the third metal layer and the fourth metal layer are spaced apart from each other and arranged asymmetrically; the first metal layer is an annular first coil layer; the second metal layer is an annular second coil layer; the third metal layer is an annular third coil layer; and the fourth metal layer is a ground layer. The load transformer further comprises a first substrate dielectric layer, a second substrate dielectric layer and a third substrate dielectric layer, wherein the first substrate dielectric layer is arranged between the first metal layer and the second metal layer; the second substrate dielectric layer is arranged between the second metal layer and the third metal layer; and the third substrate dielectric layer is arranged between the third metal layer and the fourth metal layer. The load transformer of the present invention has a small area and low cost, thereby facilitating an improvement in the utilization rate of a substrate.

Description

Load transformer and differential amplifier Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a load transformer and a differential amplifier. Background Technology

[0002] In communication technology, amplifiers are widely used for signal amplification and enhancement. In many applications, such as wireless communication, optical communication, radar, and audio amplification, amplifier performance is crucial to the overall system performance. In the design of differential amplifiers, it is often necessary to achieve the conversion between balanced signals (differential signals) and unbalanced signals (single-ended signals). Simultaneously, an impedance transformation network needs to be introduced at the output of the differential amplifier to achieve the optimal impedance transformation from the load resistance to the output of the differential amplifier. This is where the load transformer comes in as a core component.

[0003] Load transformers are used to convert balanced signals (differential signals, i.e., two signals with equal amplitude and 180° phase difference) into unbalanced signals (single-ended signals or reverse conversion). They are widely used in various applications, such as interface conversion between differential and single-ended signals, impedance matching, and improving circuit anti-interference capabilities. As shown in Figure 12, Port1 is the unbalanced port. Inputting a single-ended signal will generate two balanced signals with the same amplitude and 180° phase difference at Port2 and Port3 respectively. Conversely, when balanced signals with the same amplitude and 180° phase difference are input to Port2 and Port3 respectively, an unbalanced signal will be generated at Port1. This allows for impedance transformation, second harmonic suppression, and common-mode signal suppression.

[0004] However, commonly used coplanar coaxial and coplanar spiral transformers require a large area of ​​the coupling coil to obtain a high Q value (quality factor) and a high K value (magnetic coupling coefficient), which results in higher costs. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a load transformer to solve the problem of high cost of existing load transformers.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide a load transformer, comprising a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer stacked sequentially, wherein the first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are electrically connected to each other; the first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are spaced apart from each other and arranged asymmetrically; the first metal layer is a ring-shaped first coil layer, the second metal layer is a ring-shaped second coil layer, the third metal layer is a ring-shaped third coil layer, and the fourth metal layer is a ground layer;

[0008] The load transformer further includes a first substrate dielectric layer, a second substrate dielectric layer, and a third substrate dielectric layer; the first substrate dielectric layer is disposed between the first metal layer and the second metal layer; the second substrate dielectric layer is disposed between the second metal layer and the third metal layer; and the third substrate dielectric layer is disposed between the third metal layer and the fourth metal layer.

[0009] Preferably, the thickness of the first substrate dielectric layer is 20-25 μm, and its dielectric constant is 4.4;

[0010] The thickness of the second substrate dielectric layer is 20-25 μm, and its dielectric constant is 4.4;

[0011] The thickness of the dielectric layer of the third substrate is 90-105 μm, and its dielectric constant is 4.4.

[0012] Preferably, the first coil layer includes a first coil body in the shape of an annulus, a first connecting portion extending inward from one end of the first coil body, and a second connecting portion extending outward from the other end of the first coil body. The first connecting portion is provided with a first through hole therethrough.

[0013] The second coil layer includes a ring-shaped second coil body, a third connecting portion and a fourth connecting portion extending outward from both ends of the second coil body in the same direction, and a power supply portion extending outward from the side of the second coil body away from the third connecting portion; the power supply portion is used to connect to an external power source, and the second coil body is provided with a second through hole, and the first through hole, the second through hole and the third coil layer are electrically connected through a first wire.

[0014] The third coil layer includes a ring-shaped third coil body and a third via formed by the third coil body; a second wire passes through the third via to electrically connect and electrically connect the third coil layer to the fourth metal layer.

[0015] Preferably, the first via and the second via are positioned opposite each other.

[0016] Preferably, the first coil layer is electrically connected to the third coil layer, and the first coil layer is coupled to the second coil layer, and the unbalanced signal generated by the coupling between the two is output through the second connection portion;

[0017] Wherein, the magnetic coupling coefficient between the first coil layer and the second coil layer is k, which satisfies the following relationship:

[0018] Where M represents the mutual inductance coefficient, L1 represents the self-inductance coefficient of the first coil layer, and L2 represents the self-inductance coefficient of the second coil layer;

[0019] The quality factor of the first coil layer is Q1, which satisfies the following relationship:

[0020] Where w0 is the resonant circuit generated by the inductance and parasitic capacitance between the first coil layer and the second coil layer, L1 is the inductance of the first coil layer, and R1 is the parasitic resistance of the first coil layer.

[0021] The quality factor of the second coil layer is Q2, which satisfies the following relationship:

[0022] Where L2 is the inductance of the first coil layer and R2 is the parasitic resistance of the first coil layer.

[0023] Preferably, the first coil layer, the second coil layer, and the third coil layer are all octagonal coils.

[0024] Preferably, the first coil layer, the second coil layer, and the third coil layer are all circular coil structures.

[0025] Secondly, embodiments of the present invention provide a differential amplifier, including the load transformer as described above.

[0026] Compared with related technologies, in the embodiments of the present invention, the first metal layer, second metal layer, third metal layer, and fourth metal layer are arranged asymmetrically and spaced apart from each other; the first metal layer is a ring-shaped first coil layer, the second metal layer is a ring-shaped second coil layer, the third metal layer is a ring-shaped third coil layer, and the fourth metal layer is a ground layer; the first substrate dielectric layer of the load transformer is disposed between the first metal layer and the second metal layer; the second substrate dielectric layer is disposed between the second metal layer and the third metal layer; and the third substrate dielectric layer is disposed between the third metal layer and the fourth metal layer; this stacked transformer can achieve high Q value and high K value while significantly reducing the transformer area by reasonably using substrate dielectric layers of different thicknesses. This effectively saves the area occupied by the transformer on the substrate and improves the substrate utilization rate. Attached Figure Description

[0027] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings:

[0028] Figure 1 is a block diagram of the load transformer provided in an embodiment of the present invention;

[0029] Figure 2 is a partially exploded schematic diagram of the load transformer provided in an embodiment of the present invention;

[0030] Figure 3 is a top view of the polygonal coil of the load transformer provided in an embodiment of the present invention;

[0031] Figure 4 is a top view of the circular coil of the load transformer provided in an embodiment of the present invention;

[0032] Figure 5 is a schematic diagram of the inductance of the first coil layer in Figure 4;

[0033] Figure 6 is a schematic diagram of the quality factor of the first coil layer in Figure 4;

[0034] Figure 7 is a schematic diagram of the inductance of the second coil layer in Figure 4;

[0035] Figure 8 is a schematic diagram of the quality factor of the second coil layer in Figure 4;

[0036] Figure 9 is a schematic diagram of the magnetic coupling coefficient of the load transformer in Figure 4;

[0037] Figure 10 is a schematic diagram of the existing coplanar and coaxial form;

[0038] Figure 11 is a schematic diagram of the existing coplanar spiral form;

[0039] Figure 12 is a schematic diagram of the structure of an existing load transformer.

[0040] Among them, 100 is the load transformer, 1 is the first metal layer, 11 is the first coil layer, 111 is the first coil body, 112 is the first connection part, 113 is the second connection part, 2 is the second metal layer, 21 is the second coil layer, 211 is the second coil body, 212 is the third connection part, 213 is the fourth connection part, 214 is the power supply part, 3 is the third metal layer, 31 is the third coil layer, 32 is the third via, 4 is the fourth metal layer, 5 is the first substrate dielectric layer, 6 is the second substrate dielectric layer, 7 is the third substrate dielectric layer, 8 is the first via, and 9 is the second via. Detailed Implementation

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0042] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] Please refer to Figures 1-4. This embodiment of the invention provides a load transformer 100, comprising a first metal layer 1, a second metal layer 2, a third metal layer 3, and a fourth metal layer 4 stacked sequentially. The first metal layer 1, the second metal layer 2, the third metal layer 3, and the fourth metal layer 4 are electrically connected to each other. The first metal layer 1, the second metal layer 2, the third metal layer 3, and the fourth metal layer 4 are spaced apart and asymmetrically arranged. The first metal layer 1 is a ring-shaped first coil layer 11, the second metal layer 2 is a ring-shaped second coil layer 21, the third metal layer 3 is a ring-shaped third coil layer 31, and the fourth metal layer 4 is a ground layer. The load transformer 100 further includes a first substrate dielectric layer 5, a second substrate dielectric layer 6, and a third substrate dielectric layer 7. The first substrate dielectric layer 5 is disposed between the first metal layer 1 and the second metal layer 2; the second substrate dielectric layer 6 is disposed between the second metal layer 2 and the third metal layer 3; and the third substrate dielectric layer 7 is disposed between the third metal layer 3 and the fourth metal layer 4. By asymmetrically arranging the first metal layer 1, second metal layer 2, third metal layer 3, and fourth metal layer 4, with each layer spaced apart, the first metal layer 1 being a ring-shaped first coil layer 11, the second metal layer 2 being a ring-shaped second coil layer 21, the third metal layer 3 being a ring-shaped third coil layer 31, and the fourth metal layer 4 serving as a ground layer, the first substrate dielectric layer 5 of the load transformer 100 is disposed between the first metal layer 1 and the second metal layer 2; the second substrate dielectric layer 6 is disposed between the second metal layer 2 and the third metal layer 3; and the third substrate dielectric layer 7 is disposed between the third metal layer 3 and the fourth metal layer 4, this stacked transformer configuration allows for the efficient use of substrate dielectric layers of varying thicknesses, achieving high Q and K values ​​while significantly reducing the transformer area. This effectively saves on the substrate area occupied by the transformer and improves substrate utilization.

[0046] In this embodiment, the thickness of the first substrate dielectric layer 5 is 20-25 μm, and its dielectric constant is 4.4; the thickness of the second substrate dielectric layer 6 is 20-25 μm, and its dielectric constant is 4.4; the thickness of the third substrate dielectric layer 7 is 90-105 μm, and its dielectric constant is 4.4.

[0047] Specifically, the thickness of the first substrate dielectric layer 5 is 25 μm, and its dielectric constant is 4.4; the thickness of the second substrate dielectric layer 6 is 25 μm, and its dielectric constant is 4.4; the thickness of the third substrate dielectric layer 7 is 105 μm, and its dielectric constant is 4.4. By rationally using substrate dielectric layers of different thicknesses, high Q and high K values ​​are achieved while significantly reducing the transformer area; thus effectively saving the area occupied by the transformer on the substrate and improving substrate utilization.

[0048] In this embodiment, the first coil layer 11 includes a ring-shaped first coil body 111, a first connecting portion 112 extending inward from one end of the first coil body 111, and a second connecting portion 113 extending outward from the other end of the first coil body 111. The first connecting portion 112 has a first through hole 8 extending through it. The first coil body 111 is used for structural support, the first connecting portion 112 is used for electrical connection with the second coil layer 21, and the second connecting portion 113 is used for outputting unbalanced signals.

[0049] The second coil layer 21 includes a ring-shaped second coil body 211, a third connecting portion 212 and a fourth connecting portion 213 extending outward from both ends of the second coil body 211 in the same direction, and a power supply portion 214 extending outward from the side of the second coil body 211 away from the third connecting portion 212. The power supply portion 214 is used to connect to an external power source. The second coil body 211 has a second through-hole 9 extending through it. The first through-hole 8, the second through-hole 9, and the third coil layer 31 are electrically connected by a first wire. The third coil layer 31 includes a ring-shaped third coil body and a third through-hole 32 extending through the third coil body. The second wire passes through the third through-hole 32 and electrically connects the third coil layer 31 to the fourth metal layer 4. After the third connection part 212 and the fourth connection part 213 are used to input balanced signals with the same amplitude respectively, they are electrically connected through the first via 8 and the second via 9, so that the second coil layer 21 and the first coil layer 11 form a transformer coupling. Then, an unbalanced signal is generated through the second connection part 113 of the first coil layer 11. At this time, impedance transformation, second harmonic suppression, and common mode signal suppression can be realized.

[0050] In this embodiment, the first via 8 and the second via 9 are arranged facing each other along the axial direction. This facilitates the electrical connection between the first coil layer 11 and the second coil layer 21.

[0051] In this embodiment, the first coil layer 11 is electrically connected to the third coil layer 31, and the unbalanced signal generated by the coupling between the first coil layer 11 and the second coil layer 21 is output through the second connection part 113.

[0052] The magnetic coupling coefficient between the first coil layer 11 and the second coil layer 21 is k, which satisfies the following relationship: M represents the mutual inductance coefficient, L1 represents the self-inductance coefficient of the first coil layer 11, and L2 represents the self-inductance coefficient of the second coil layer 21. The magnetic coupling coefficient k is related to the substrate stack, the coupling area of ​​the first coil layer 11 and the second coil layer 21, etc.

[0053] The quality factor of the first coil layer 11 is Q1, which satisfies the following relationship: Where w0 is the resonant circuit formed by the inductance and parasitic capacitance between the first coil layer 11 and the second coil layer 21, L1 is the inductance of the first coil layer 11, and R1 is the parasitic resistance of the first coil layer 11. This quality factor is related to the substrate stacking, shape, and area of ​​the first coil layer 11.

[0054] The quality factor of the second coil layer 21 is Q2, which satisfies the following relationship:

[0055] Wherein, L2 is the inductance of the first coil layer 11, and R2 is the parasitic resistance of the first coil layer 11.

[0056] Specifically, taking a circular load transformer 100 as an example, the area of ​​this load transformer 100 is 1.16 mm². 2 When balanced signals (differential signals) are input to the third connection portion 212 and the fourth connection portion 213 of the second coil layer 21, the power supply portion 214 is used to treat the radio frequency equivalent as ground. The unbalanced signal generated by coupling with the second coil layer 21 and the third coil layer 31 is output at the port of the second connection portion 113. The higher k and Q are, the lower the insertion loss generated by the transformer, and the better the output performance of the power amplifier.

[0057] In this embodiment, the first coil layer 11, the second coil layer 21 and the third coil layer 31 are all octagonal coils.

[0058] In this embodiment, the first coil layer 11, the second coil layer 21 and the third coil layer 31 are all circular coil structures.

[0059] In this embodiment, Figures 5-9 show the simulation parameters of the circular coil load transformer 100 of Figure 4. Inductance L1 is the inductance of the circular coil connecting the first metal layer 1 to the third metal layer 3, and Q1 is the quality factor of inductance L1. Inductance L2 is the inductance of the circular coil in the second metal layer 2 where the third connecting part 212 and the fourth connecting part 213 are located, and Q2 is the quality factor of inductance L2. L1 = 2nH, Q1 = 52; L2 = 0.57nH, Q2 = 44; magnetic coupling coefficient k = 0.75. Figure 10 shows the existing coplanar coaxial transformer with k values ​​between 0.3 and 0.5, and Figure 11 shows the existing coplanar spiral transformer with k values ​​between 0.5 and 0.7. The stacked circular load transformer 100 of this invention has a k value higher than 0.7, which can reduce the insertion loss of the transformer and improve the output performance of the differential amplifier.

[0060] Example 2

[0061] This invention provides a differential amplifier, including the load transformer 100 as described above. The technical effects produced by the differential amplifier in this embodiment are the same as those in Embodiment 1, and will not be described again here.

[0062] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. A load transformer, comprising a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer stacked sequentially, wherein the first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are electrically connected to each other; characterized in that, The first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are spaced apart from each other and arranged asymmetrically; the first metal layer is a ring-shaped first coil layer, the second metal layer is a ring-shaped second coil layer, the third metal layer is a ring-shaped third coil layer, and the fourth metal layer is a ground layer; The load transformer further includes a first substrate dielectric layer, a second substrate dielectric layer, and a third substrate dielectric layer; the first substrate dielectric layer is disposed between the first metal layer and the second metal layer; the second substrate dielectric layer is disposed between the second metal layer and the third metal layer; and the third substrate dielectric layer is disposed between the third metal layer and the fourth metal layer.

2. The load transformer according to claim 1, characterized in that, The thickness of the first substrate dielectric layer is 20-25 μm, and its dielectric constant is 4.4; The thickness of the second substrate dielectric layer is 20-25 μm, and its dielectric constant is 4.4; The thickness of the dielectric layer of the third substrate is 90-105 μm, and its dielectric constant is 4.

4.

3. The load transformer according to claim 1, characterized in that, The first coil layer includes a first coil body in the shape of a ring, a first connecting portion extending inward from one end of the first coil body, and a second connecting portion extending outward from the other end of the first coil body. The first connecting portion is provided with a first through hole. The second coil layer includes a ring-shaped second coil body, a third connecting portion and a fourth connecting portion extending outward from both ends of the second coil body in the same direction, and a power supply portion extending outward from the side of the second coil body away from the third connecting portion; the power supply portion is used to connect to an external power source, and the second coil body is provided with a second through hole, and the first through hole, the second through hole and the third coil layer are electrically connected through a first wire. The third coil layer includes a ring-shaped third coil body and a third via formed by the third coil body; a second wire passes through the third via to electrically connect and electrically connect the third coil layer to the fourth metal layer.

4. The load transformer according to claim 3, characterized in that, The first through hole and the second through hole are arranged opposite each other along the axial direction.

5. The load transformer according to claim 3, characterized in that, The first coil layer is electrically connected to the third coil layer, and the first coil layer is coupled to the second coil layer. The unbalanced signal generated by the coupling between the two is output through the second connection part. Wherein, the magnetic coupling coefficient between the first coil layer and the second coil layer is k, which satisfies the following relationship: Where M represents the mutual inductance coefficient, L1 represents the self-inductance coefficient of the first coil layer, and L2 represents the self-inductance coefficient of the second coil layer; The quality factor of the first coil layer is Q1, which satisfies the following relationship: Where w0 is the resonant circuit generated by the inductance and parasitic capacitance between the first coil layer and the second coil layer, L1 is the inductance of the first coil layer, and R1 is the parasitic resistance of the first coil layer. The quality factor of the second coil layer is Q2, which satisfies the following relationship: Where L2 is the inductance of the first coil layer and R2 is the parasitic resistance of the first coil layer.

6. The load transformer according to claim 1, characterized in that, The first coil layer, the second coil layer, and the third coil layer are all octagonal coils.

7. The load transformer according to claim 1, characterized in that, The first coil layer, the second coil layer, and the third coil layer are all circular coil structures.

8. A differential amplifier, characterized in that, Including the load transformer as described in any one of claims 1-7.

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